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Update 2016s3 week 12
Using iRacing's DX11
Without logical reason FPS (frame rate) was dropping too low
As a fix, I used the same settings (that I used with DX9) including turning on Adaptive Vsync in nVidia control panel
Result: everything running smooth again. I make no claims what it will do for you.
Note, the "program to customize" for DX11: iracingsim64dx11.exe located in c:/program files (x86)/iracing
My Nvidia 3d settings screenshot.

2016s2added new page: DirectX_11.
iRacing previously used DirectX 9 (and currently does by default).
Everything on this page was written prior to DX 11

2016s1 applicable to any new build but seemed important this build.
After downloading the new build.
Renamed renderer.ini and app.ini in Documents/iRacing/
Then ran the sim which re-ran the graphics wizard and re-created the files.
After playing around in the sim, I exited, waited a minute, then used http://kdiff3.sourceforge.net/ to compare & edit new/old files.
* Don't edit files while sim is open. Make a copy of files before butchering them.

2016s1 Video memory slider (copied from release notes)
- The Video Memory slider on the graphics option screen now goes up to 4GB to accommodate newer tracks and GPUs.
- The System Memory Working Set slider now goes up to 8GB when running the 64-bit version of the simulator. Separate system memory slider settings for the 32-bit and 64-bit versions of the simulator are now maintained in the "renderer.ini" file. The new 64-bit setting will default to 2GB less than the RAM installed on the PC, but this value is also clamped between 2GB and 8GB.

Post(s) by Shawn N re Video memory at Nurburgring.

Minimum specspost: "In a 32-bit OS, each process only gets 2GB of memory for it's use, even if the PC has 16 GB. There is a boot option in some 32-bit versions of windows to increase this to about 3GB. As far as I know the 'Ring will not load in 2GB of address space. And, if it will load in 3GB depends on the PC and your settings. Lowering you system memory slider to about 1200MB will ensure it loads in the smallest footprint possible, but the 'Ring requires a 64-bit OS honestly to load. I can load it running the 32-bit sim in Windows 7 64-bit if my memory slider is reasonably low on the graphics options screen."

Post(s): "Check the memory sliders in the graphics options. Textures can drop quality to fit into video memory primarily but also to fit into system memory. In 64 bit just set your system mem slider to be about 2gb under your amount system ram. In 32 bit you really only want to set this slider up to about 2400mb max, due to 32bit address space limitations. Set your video mem slider to the amount of dedicated ram in your GPU or slightly less if getting large pauses when driving. Textures will drop quality to fit within your systems capability. For best quality you need a 2gb+ gpu and a 6gb+ system with a 64 bit OS and the 64 bit simulator.
Setting those sliders too high will only cause problems so don't do that to get quality your PC isn't capable of delivering with acceptable performance."
"If unsure how to set the sliders run the graphics autoconfig and it will set them at reasonable levels for your system (should do anyway)."
"You may also increase texture quality by disabling certain options that require extra memory such as depth of field effects, 2048 res car textures, shadow volumes, etc."

NumBumRing will not run well on 32 bit system. Also 32 bit system support ending March 2016. Staff post (12 Dec 2015).

2016s1 PopcornFX (copied from release notes)
- PopcornFX is a new particle system for iRacing that greatly enhances the audio/visual experience of vehicles interacting with the world. The system manages everything from smoke clouds and grass particles, to marbles and sparks. If your computer can handle it, crank your graphics settings up to the maximum for a hyper-realistic racing experience!

Update 2015s4 new build post re frame rates
Enabling dynamic track rendering can cost 10% to 18% FPS generally.
Also setting particle detail to HIGH may cost 5% or so.
Would be interesting to know if setting particles to MED helps, or if turning off dynamic track rend

Update 2015s4 from release notes: Borderless Window Support.
The sim can now be run in windowed mode without a border or title bar.
There is a new option on the auto-config dialog and a new graphics option to disable the border.
Like the full screen toggle in options, the border configuration does not take effect until the sim is restarted.

3 monitors flat / no angle post: Select one monitor if you are lining them up in a row (no angles) and treat them like one large monitor, no render seperately. In this case you want to use the bezel correction built into your graphics card as well.

Step: Dump the heat, with EVGA PrecisionX.
See JK's thread for instructions; I didn't do it.

Step: (Advanced) iRacing renderer.ini settings.
In documents/iRacing/renderer.ini (edit in notepad or similar, NOT while in a session):
Jacob notes the following tweaks in the file:
- Turn off the mirror optimizations, so that EVERY mirror is updated on EVERY frame
- Tweak headlights for maximum quality (color and dynamic)
- Load textures while driving (so I can immediately see updated custom paints without having to exit my car)
- Tweak compression options (I have enough GPU RAM to leave all 3 options uncompressed; see warning below)
- Set LODPct, OcclusionCull, and TwoBackBuffers to certain values, for best quality and performance.
Full details in JK's thread.
I set TwoBackBuffers to 1 based on other advice, JK is recommending 0.
I've noted my renderer.ini files at the bottom of APPini page.

Nvidia Control Panel > Manage 3d settings > Program Settings:
(In one of the steps above I had already added iracingsim64.exe to the program list).
At bottom of list, "Vertical sync", I changed to "Adaptive".
I had also previously set "maximum pre-rendered frames" to 1.

In documents/iRacing/renderer.ini TwoBackBuffers=1 (it was 0).
Don't edit any .ini files while the sim is running.

After changes, my FPS (frames per second) were capped to the monitor's refresh rate (60).
I've read others prefer to let the FPS run as high as it wants to go.
My very limited understanding and interpretation:
Running high/unlocked FPS can cause tearing.
Running unlimited FPS may mean a better appearance while hardware works harder and hotter.
Running vsync adaptive provides me with a terrific display at lower FPS and my system appears to be running cooler.
Most importantly, enabling vsync adaptive (in Nvidia, not in-game) resolved an issue my system had with iRacing.

4. Read forum thread 3 screens, Side monitor angle (or start with Sebastien's post page 2).>FOV & ANGLE CALCULATORS ADDED TO MY FOV PAGE.
While the whole thread is good reading, Sebastien Tixier's post on page 2 is priceless.
Using his file in a free program (geogebra) made calculating side monitor angle and FOV extremely easy.

As linked in Sebastien's post, install geogebra.

Download Sebastien's file.

Run / double click Sebastien's file and it opens in geogebra, then drag the dots.

"Render each screen separately" enabled. 2016s4: it doesn't say "render each screen separately" any more
now enable Multi-Projection - see DX11 page for more)
If I disabled it, the sim displays 4 wheels on the front of my car thus I left it enabled.
I've also read it is recommended to enable it.

Number of screens 3.

Enter the values for monitors and distance and angle.
"Visible width excluding bezel" - measure horizontal width of monitor viewing area.
"Monitor width including bezel" - measure width of monitor from edge to edge.
"Viewing distance" - measure distance from center screen to your eyeballs.
I originally read this on Derek Speare's forum post.
To measure angle, I bought a 50c protractor from a local shop.
Google protractor to print one out.

Have you adjusted your memory sliders yet? Good luck!Note: 2016s1 memory sliders have changed - no longer need to tweak .ini files
Check Jacob's forum thread - he may have new advice.
Look for "Graphics Tab - Display section".
He did discuss GPU Video Memory (MB) and Max system memory to use (MB).

For over 2gb, you need to edit MaxWorkingSetMB= in file renderer.ini
If you touch the in-sim memory sliders after editing that line, it will reset to default 2GB.

Regardless of your system, maximum settings can cause conflicts with iRacing's programming.
Shawn Nash (iRacing staff) started a memory slider thread in 2011 worth reading.2016s1 I still have this disabled:
Disabling "Video mem swap high-res cars" (in-game option) improved my system's performace.
After trial and error with the in-game sliders, I'm currently using these settings.

Even with small teething hiccups, iRacing is awesome on 3 monitors.
Definitely worth the effort.

A quick test video. Gear displayed on iPhone for #99 with iSpeed's webserver.
Side view, car #99 slightly elongated. To fix: set correct "angle between center and side screens" and FOV.

Another clip to answer a question.

Richard, this clip is my answer to your question.
The monitor ends are missing - I was too close with my camera/phone.
Going across the top of Mt Panorama with DM next to me and AH up the clacker.
AH is seen in the door mirrors.
On 1 monitor I couldn't use both door mirrors if any.
3 monitors with wide FOV gives me the confidence to defend harder (and keep it clean).
Too often I gave away too much track on single monitor - where is he?!
Depending on car - still expect blind spots with 3 monitors.
I wouldn't necessarily say I'm driving faster, I'm definitely driving better.
Spacial awareness / positioning on track has improved immensely.
DM would agree because I didn't take him out.

• CONNECTING A 4TH MONITOR - how not to do it.

In theory it is very easy to connect a 4th monitor with a GTX760 & Nvidia's control panel.
In reality the software didn't make it easy.
I now understand why some people are using different software (not Nvidia's).

Open Nvidia control panel - so far so good.
Ensured surround group still active and 4th monitor is additional monitor.
Still looking good, the 4th monitor is like an extended desktop.
Tried a test session in iRacing, all looking terrific.

End result, I scrapped the idea of a 4th monitor.
To stop Nvidia from crashing I had to uninstall/reinstall.

If it ain't broke don't fix it.
After installing the current driver my system was stable and I left it at that.

Rolling back to Nvidia driver 327.23 has resolved some issues for others, I haven't tried it.

Update: I connected 4th monitor via USB - it was an impulse fix.
My local computer shop recommended & supplied FY-1016A USB 2.0 UGA Multi-Display Adapter (image).
It works great except for spreading the taskbar over 3 monitors when enabled.
Install was easy - plugged into USB port on computer, windows loaded drivers.
Then connected monitor (TV actually, via Digitech AC-1706 HDMI switchbox with remote).
New icon in taskbar loaded for "DisplayLink Manager" software.
Click to extend desktop or turn off (image).
Click on video settings to move 4th monitor position.
I use desktop links (replace | with a backward slash):
Turn off extended mode %windir%|System32|DisplaySwitch.exe /internal
Turn on extended mode %windir%|System32|DisplaySwitch.exe /extend
Everything is working very well with 4 monitors - I definitely won't be trying an Nvidia driver update.
(Desktop icons get moved if I don't change settings in the same on/off order).
Change Windows theme to mine for iRacing | Swap TV input to computer | Displaylink Extend
Disclaimer: I'm not suggesting you buy these products nor endorsing them. It was an impulse purchase.

• TASKBAR NOT CONFINED TO CENTRE MONITOR - not related to USB above.

Nvidia control panel > Desktop (on tool bar) > Surround Displays > "Confine Taskbar To Center Display".
My taskbar randomly moves from centre monitor; reason unknown.
Unticking/ticking the confine option fixes it.
Sometimes clicking on the taskbar fixes it too.
Found a quick fix on Google: run "tskill dwm" (use at your own risk).
That line reportedly resets the desktop manager. (I personally make no claims to it's purpose).
To make it easier, I created a .cmd file that sits on my desktop with 2 linesstart tskill dwm

exit

• Some of Jacob's thread revisions & updates since my upgrade.I don't expect to try them before my next hardware upgrade- see his thread for more revisions.I stopped noting Jacob's revisions - see his thread

23.08.14 forum post.
* Added Step 10: (Advanced) Determine Max Stable Boost Clock on a Kepler, with Heaven 4.0.
This will help you shake out instability, so you can be sure to race without fear of the GPU crashing!
* Tweaked Step 11 to include my new values for "Max Stable Boost" clocks.

Jacob has made more revisions, I'm still using my original settings. (Read his thread for his current suggestions).

Normally, uninstalling from Programs and Features will do the trick, but there are times when you need *all* traces removed. So....

For uninstalling *all* traces of NVIDIA drivers, I recommend the following steps in order:
- Control Panel -> System -> Advanced system settings -> Hardware tab -> Device Installation Settings -> "No, let me choose what to do" with "Never install driver software from Windows Update". This way, Windows Update will not try to install any driver version, allowing you full control over whatever version you want to play with.
- In Programs and Features, uninstall the "NVIDIA Graphics Driver" entry, restarting if prompted
- In Programs and Features, uninstall any NVIDIA remnants, restarting if prompted (saving NVIDIA HD Audio Driver for last, since it for sure involves a restart)
- Create a System Restore Point, just to be absolutely safe in case DDU has an issue in the next step. Control Panel -> System -> Advanced system settings -> System Protection tab -> Create
- Use Display Driver Uninstaller (DDU), even if you're not in Safe Mode it is okay. This tool will remove ALL remnants of the driver, and should automatically restart when done. http://www.wagnardmobile.com/DDU/ Note: This tool is actually recommended by NVIDIA in cases where their installer/uninstaller does not behave properly.
- Install whatever driver version you were wanting, restarting if prompted.

From member Sean H's thread "CLEAN INSTALL YOUR GPU DRIVERS!!!" (09/2016)
I suggest reading the thread for comments about DDU.

Extract from Sean's post:

How To Do A TRUE Clean Install

With that being said, there is a tool out there that will cleanly remove any and ALL Nvidia drivers (and AMD drivers if you're having issues for the Red Team). Display Driver Uninstaller removes every trace of your GPU's drivers and paves the way for true clean installs. The download link is below.

And that's it. 4 steps and you have a clean install of your graphics drivers. I've been seeing and hearing a lot about how this new build has been killing frame rates (particularly on the 970 cards) and wanted to try this method to see if it would remedy things, which it has in the past.

Again, I recommend that you do this every time you update your drivers! It takes a little extra time, yes. But it ensures that your graphics drivers are not at fault.